Method and System for Casting Metal Using a Riser Sleeve with an Integral Mold Cavity Vent

ABSTRACT

A metal casting riser sleeve system includes a mold cavity and a vented riser sleeve. The vented riser sleeve includes a riser reservoir and a vent passage. The riser reservoir is fluidly connected to the mold cavity and configured to allow molten alloy to flow from the mold cavity to the vented riser sleeve to create a casting portion. The vent passage extends through a length of the vented riser sleeve to allow airflow from the mold cavity through the vent passage.

TECHNICAL FIELD

The present disclosure is related to methods and systems for casting metal, and more particularly to methods and systems for casting metal using a riser sleeve with an integral mold cavity vent.

BACKGROUND

Foundries produce metal castings using a casting process. The casting process is characterized by using mold material. A frame or mold box known as a flask contains the molding material. A foundryman creates mold cavities by compacting molding material around mold patterns within the flask. The metal casting is formed by filling the mold cavities with molten metal. Molten metal may shrink when cooling to form solid metal. Shrinkage may create voids in a metal casting. Voids may cause the solidified metal to become less structurally sound. Voids may further alter the solidified metal's shape to an unintended shape. To prevent the shrinkage, a reservoir known as a riser is built into the mold. Risers provide molten metal to the casting as it solidifies so that any voids form in the riser and not in the casting. As molten metal fills the mold cavity, gases may become trapped in the mold cavity. Gases in the mold cavity may create voids in the solidified metal.

SUMMARY

The teachings of the present disclosure relate to a system and a method for casting metal using a vented riser sleeve. In accordance with one embodiment, a metal casting system includes a mold cavity and a vented riser sleeve. The vented riser sleeve includes a riser reservoir and a vent passage. The riser reservoir is fluidly connected to the mold cavity and configured to allow molten alloy to flow from the mold cavity to the vented riser sleeve. The vent passage extends through a length of the riser sleeve portion to allow airflow from the mold cavity through the vent passage.

According to another embodiment, a metal casting system includes a molding flask and a vented riser sleeve. The molding flask includes a drag mold portion comprising external and internal drag mold walls. The molding flask includes a cope mold portion comprising external and internal cope mold walls. The internal drag mold walls and internal cope mold walls form, at least in part, a mold pattern cavity representative of a mold pattern. The vented riser sleeve comprises a riser reservoir fluidly connected to the mold pattern cavity and configured to allow molten alloy to flow from the mold cavity to the vented riser sleeve. The vented riser sleeve comprises a vent passage that extends through a length of the vented riser sleeve to allow airflow from isolated spots in the mold cavity through the vent passage.

According to another embodiment, a method is provided for casting metal includes positioning a vented riser sleeve system within in a flask comprising a mold cavity, the vented riser sleeve extending at least from the flask to the mold cavity. The vented riser sleeve includes a riser reservoir fluidly connected to the mold pattern cavity and configured to allow molten alloy to flow from the mold cavity to the vented riser sleeve to create a casting portion. The vented riser sleeve includes a vent passage that extends through a length of the vented riser sleeve to allow airflow from the mold cavity through the vent passage. The method further includes removing the vented riser sleeve from the casting portion.

Certain embodiments may provide one or more technical advantages. In some embodiments, the vented portion of the riser sleeve allows evacuation of hot gasses that build up in isolated sections of a mold. A traditional method requires foundrymen to create a hole to evacuate the gas. For example, foundrymen may drill a hole through a mold cavity. The traditional method may be time and labor intensive. Further, the traditional method is subject to human error as foundrymen may forget to drill the hole. Another technical advantage of particular embodiments is ensuring a clean metal casting. In the traditional method, foundrymen may introduce debris in the mold when drilling the hole. Yet another technical advantage of particular embodiments is ensuring that the coordinates of a vent are consistently located across casting molds. This improves the consistency, quality, and reliability of metal castings created using the casting molds. The current disclosure contemplates a clean, pre-formed vent passage that allows gasses to escape the mold cavity.

Other technical advantages will be readily apparent to one of ordinary skill in the art from the following figures, descriptions, and claims. Moreover, while specific advantages have been enumerated above, various embodiments may include all, some, or none of the enumerated advantages.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of particular embodiments will be apparent from the detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 illustrates a metal casting system with a vented riser sleeve, in accordance with particular embodiments;

FIG. 2 illustrates a cross-sectional view of a vented riser sleeve, in accordance with particular embodiments;

FIG. 3 illustrates a cross-sectional view of a vented riser sleeve, in accordance with particular embodiments;

FIG. 4 illustrates an overhead view of a vented riser sleeve system, in accordance with particular embodiments;

FIG. 5 illustrates a cross-sectional view of a vented riser sleeve, in accordance with particular embodiments;

FIG. 6 illustrates a vented riser sleeve comprising a plurality of vent passages, in accordance with particular embodiments;

FIG. 7 illustrates a vented riser sleeve system for casting a wheel, in accordance with particular embodiments;

FIG. 8 illustrates a cross-sectional view of the vented riser sleeve system of FIG. 6, in accordance with particular embodiments;

FIG. 9 illustrates a partial overhead view of the vented riser sleeve system of FIG. 6, in accordance with particular embodiments;

FIG. 10 illustrates a partial view of the vented riser sleeve system of FIG. 6, in accordance with particular embodiments;

FIG. 11 illustrates a partial cross-sectional view of the vented riser sleeve system of FIG. 6, in accordance with particular embodiments; and

FIG. 12 is flowchart depicting a method for casting metal using a vented riser sleeve system, in accordance with particular embodiments.

DETAILED DESCRIPTION

Foundries produce metal castings using a casting process. The casting process is characterized by using mold material. A frame or mold box known as a flask contains the molding material. A foundryman creates mold cavities by compacting molding material around mold patterns within the flask. The metal casting is formed by filling the mold cavities with molten metal. Most metals shrink upon cooling. To prevent the shrinkage from creating voids in the metal casting, a reservoir known as a riser is built into the mold. Risers provide molten metal to the casting as it solidifies so that any voids form in the riser and not the casting.

As molten metal solidifies, gases may become trapped in the mold cavity. Gases in the mold cavity may create voids in the solidified metal. Voids may cause the solidified metal to become less structurally sound. Voids may further alter the solidified metal's shape to an unintended shape. Thus, gases are generally removed from the mold cavity during the casting process. In the traditional process, a foundryman creates a hole directly in the mold cavity. For example, a foundryman may drill a hole through the mold cavity. This process may be time and labor intensive. Further, this process is subject to human error. For example, a foundryman may forget to drill a hole or drill an incorrect hole. Additionally, drilling a hole may create debris of impurities in the metal casting. This disclosure contemplates utilizing a vented riser sleeve to efficiently allow gas to escape the molding cavity while creating a clean metal casting.

FIG. 1 is a cross-sectional view of a metal casting system 10, in accordance with particular embodiments. Metal casting system 10 includes a flask 22 into which a foundryman pours molten metal, such as liquid steel, to form a metal casting. Flask 22 comprises a drag mold portion 12 and a cope mold portion 14. The cope and drag mold portions both comprise molding material 18 that defines a mold cavity 16. Flask 22 forms a frame around the mold portions. The shape of flask 22 may be square, rectangular, round, or any convenient shape suitable to contain the pattern defining mold cavity 16. Flask 22 may be made of steel, aluminum, wood, or any material suitable for containing molding material 18 and molten alloy. One of skill in the art would also recognize that flask 22 may comprise more than two mold portions, depending on the complexity of the mold pattern. A foundryman may use a high pressure process and molding pattern to create the internal walls of mold cavity 16. The walls define at least in part the surfaces of the cavity into which a foundryman pours the molten alloy, and where the molten alloy solidifies, during the metal casting process. Molding material 18 may comprise green sand. Green sand may include a combination of sand, water, and/or clay. In particular embodiments, molding material 18 may comprise metal particles such as steel shot. Embodiments may utilize other suitable materials, such as other types of molding sand or plaster, to make up the cope and drag molds. In some embodiments, the sand casting process may include chemically bonded molds, plaster molds, no bake molds, or vacuum process molds.

Metal casting system 10 also includes a sprue 20 and a vented riser sleeve 100. Sprue 20 is a passageway through which a foundryman introduces molten alloy into mold cavity 16. One end of sprue 20 forms an opening in an external wall of flask 22, and another end connects to mold cavity 16. The cope and drag mold portions support sprue 20. Vented riser sleeve 100 insulates a riser reservoir 105. Riser reservoir 105 receives molten alloy after it flows through sprue 20 and mold cavity 16. A top end of riser reservoir 105 forms an opening in an external wall of flask 22. A bottom end of riser reservoir 105 connects to mold cavity 16. Vented riser sleeve 100 comprises a vent passage 110. Vent passage 110 generally allows air to from mold cavity 16 out of flask 22. Vent passage 110 may run throughout riser sleeve 100, from cavity to 16 to the outside of mold casting system 10.

When implementing particular embodiments of metal casting system 10, a foundryman packs molding material 18 around various patterns to form mold cavity 16 and sprue 20. The foundryman inserts riser sleeve 100 between mold cavity 16 and an external wall of flask 22. One of skill in the art would recognize that both the positioning and the number of passageways, such as sprues and riser reservoirs, may vary depending on various factors such as the mold pattern and the metal alloy used in a particular metal casting. The foundryman assembles flask 22 by coupling drag mold portion 14 to cope mold portion 12. The foundryman then pours molten alloy into sprue 20. The molten alloy flows through sprue 20 where it fills mold cavity 16 and riser reservoir 105. In some embodiments, the foundryman may pour molten alloy directly into riser reservoir 105. As the molten alloy solidifies and shrinks in mold cavity 16, molten alloy flows from riser reservoir 105 back into mold cavity 16 to compensate for shrinkage.

Particular embodiments may provide for more efficient solutions, for example, when evacuating air from mold cavity 16. Vented riser sleeve 100 comprises vent passage 110, which allows air to pass from mold cavity 16 out of flask 22. Because the foundryman is not drilling a hole near the riser sleeve 100, system 10 is less susceptible to human error. As another example, the preformed vent passage 110 reduces labor costs of manually drilling a hole in the flask 22. As yet another example, mold cavity 16 does not receive impurities caused by drilling. FIGS. 2-5 further illustrate vented riser sleeve 100, in accordance with particular embodiments. Vented riser sleeve 100 may be made from any refactory material (e.g., sand, insulating fiber, exothermic fiber, or any combination of such materials) suitable for containing the metal allow used in the metal casting process. One of skill in the art would select a suitable material based on the desired insulating or exothermic properties. As illustrated, vented riser sleeve 100 comprises riser reservoir 105, vent passage 110, and lip portion 115. Vented riser sleeve 100 may be connected, directly or indirectly, to breaker 125 and/or casting 120. Generally, riser reservoir 105 receives molten alloy. For example, molten alloy fed through sprue 120 may flow through mold cavity 16 to riser reservoir 105. As another example, molten alloy may be poured directly into riser reservoir 105. Regardless of how riser reservoir 105 receives molten alloy, the alloy may be fed into mold cavity 16 to facilitate creating casting 120. For example, the molten alloy may solidify in mold cavity 16 to form casting 120. Casting 120 may be any shape as defined, at least in part, by mold cavity 16. In an embodiment, casting 120 may be, at least in part, a wheel. For example, casting 120 may be a railcar wheel. Casting 120 may comprise any type of metal alloy or any other suitable type of material. In an embodiment, casting 120 may be a steel casting 120.

A vented riser sleeve system may further comprise lip portion 115 which is part of vented riser sleeve 100. As illustrated, lip portion 115 of vented riser sleeve 100 extends to a portion of casting 120 that is higher relative to other portions of casting 120. Lip portion 115 may comprise vent passage 110. In some embodiments, vent passage 110 may not be in lip portion 115. Vent passage 110 may be located in any suitable location of vented riser sleeve 100. Generally, vent passage 110 allows air to escape from isolated areas of mold cavity 16. For example, as molten alloy solidifies, it may create air in mold cavity 16. For example, air pockets may form in mold cavity 16. Air pockets may create voids in casting 120, thus reducing the structural integrity of casting 120. Vent passage 110 may allow air to be released from mold cavity 16. In some embodiments, vent passage 110 is a preformed hole that extends throughout vented riser sleeve 100. Vent passage 110 may be any suitable shape. For example, vent passage 110 may be cylindrically shaped. As another example, vent passage 100 may be a rectangular shape.

As illustrated, vented riser sleeve 100 is connected to breaker 125. In some embodiments, breaker 125 reduces the section of metal that connects casting 120 to vented riser sleeve 100. Breaker 125 facilitates removal of vented riser sleeve 100 from casting 120. For example, breaker 125 may allow vented riser sleeve 100 to be removed from casting 120 by impacting vented riser sleeve 100 and/or casting 120. In some embodiments, breaker 125 is a Washburn core. In certain embodiments, system 100 may not comprise breaker 125. In these embodiments vented riser sleeve 100 may still be removed from casting 120. For example, vented riser sleeve 100 may be cut from casting 120, such as through a thermal cut from casting 120 with an oxy-acetylene torch.

Particular embodiments may provide for more efficient solutions, for example, when evacuating air from mold cavity 16. Vented riser sleeve comprises vent passage 110, which allows air to pass from mold cavity 16 out of flask 22. Because the foundryman is not drilling a hole near the riser sleeve 100, system 10 is not susceptible to human error. As another example, the preformed vent passage 110 reduces labor costs of manually drilling a hole in the flask 22. As yet another example, particular embodiments reduce manufacturing costs by reducing or eliminating expenses associated with replacing drill bits used to create holes high abrasion media. As yet another example, mold cavity 16 does not receive impurities caused by drilling.

FIG. 6 illustrates a vented riser sleeve comprising a plurality of vent passages, in accordance with particular embodiments. As illustrated, vented riser sleeve 100 comprises riser reservoir 105 surrounded by a plurality of vent passages 110. In an embodiment, mold cavity 16 may be shaped in a way such that a single vent passage 110 is not sufficient to evacuate the air in mold cavity 16. For example, mold cavity 16 may comprise a plurality of chambers or a plurality of elevations. In an embodiment, vented riser sleeve 100 may comprise a plurality of vent passages 100. For example, vented riser sleeve 100 may comprise eight vent passages 100. As illustrated, vent passages 110 may be placed at the perimeter of riser reservoir 105. Vent passages 110 may be placed in any suitable location on vented riser sleeve 100. Vented riser sleeve may have any suitable number of vent passages 100.

FIGS. 7-11 illustrate a vented riser sleeve system for casting a wheel, in accordance with particular embodiments. As discussed, vented riser sleeve 100 may be any suitable shape and may be used to facilitate creating any suitable casting 120. In the embodiments illustrated in FIGS. 7-11, vented riser sleeve 100 facilitates casting at least a portion of, a wheel. For example, vented riser sleeve 100 may facilitate creating a railcar wheel. As illustrated, lip portion 115 of vented riser sleeve 100 aligns with the outer area of the wheel, which has a relatively high elevation. Vent passage 110 may extend to the highest portion of mold cavity 116. Vent passage 110 may extend to an isolated area of mold cavity 16. Vented riser sleeve 100 is shaped such that the bottom portion of vented riser sleeve 100 is flush with, or substantially flush with, casting 120.

Particular embodiments may provide for more efficient solutions, for example, when evacuating air from mold cavity 16. Vented riser sleeve comprises vent passage 110, which allows air to pass from mold cavity 16 out of flask 22. Because the foundryman is not drilling a hole near the riser sleeve 100, system 10 is not susceptible to human error. As another example, the preformed vent passage 110 reduces labor costs of manually drilling a hole in the flask 22. As yet another example, mold cavity 16 does not receive impurities caused by drilling.

FIG. 12 is a flowchart depicting a method for casting metal using a vented riser sleeve, in accordance with particular embodiments. Method 1200 begins at step 1205 where a foundryman prepares the flask for molding. The foundryman packs molding material 18 around a mold pattern contained in flask 22. Flask 22 is separable into at least two portions, drag mold portion 12 and cope mold portion 14, to facilitate removal of the mold pattern from molding material 18. Removal of the mold pattern creates mold cavity 16. In a similar fashion, a foundryman forms sprue 20 by pressing and removing a dowel, or any pattern sufficient to create a passageway connecting the external wall of flask 22 to mold cavity 16, into molding material 18. The foundryman also inserts vented riser sleeve 100 between mold cavity 16 and the external wall of flask 22. The number and the positioning of the sprue(s) and riser sleeve(s) 100 may vary depending on various factors such as the mold pattern and the metal alloy being used.

At step 1210, the foundryman pours molten alloy into sprue 120 and/or riser reservoir 105. The molten alloy flows into mold cavity 16. As the molten alloy solidifies and shrinks in mold cavity 116, molten alloy flows from riser reservoir 105 back into mold cavity 16 to compensate for the shrinkage. As the molten alloy solidifies, air pockets may be formed in mold cavity 16. Vent passage 110 allows the air to escape mold cavity 16. The method is complete when the molten alloy has solidified to form casting 120. The foundryman removes vented riser sleeve 100 from casting 120 before the method ends.

Modifications, additions, or omissions may be made to the method described herein without departing from the scope of the present disclosure. For example, the steps may be combined, modified, or deleted where appropriate, and additional steps may be added. Additionally, the steps may be performed in any suitable order.

Although embodiments of the present disclosure and their advantages have been described in detail, it should be understood that various other changes, substitutions, and alterations may be made hereto without departing from the spirit and scope of the invention as defined by the claims below. As another example, although particular steps have been described as being performed by a foundryman (e.g., pouring molten alloy, etc.) many of those steps may also be machine automated. 

What is claimed is:
 1. A metal casting system, comprising: a mold cavity; and a vented riser sleeve comprising: a riser reservoir fluidly connected to the mold cavity and configured to allow molten alloy to flow from the mold cavity to the vented riser sleeve; and a vent passage extending through a length of the vented riser sleeve to allow airflow from the mold cavity through the vent passage.
 2. The system of claim 1, wherein the vent passage is cylindrically shaped.
 3. The system of claim 1, wherein the vent passage is rectangularly shaped.
 4. The system of claim 1, wherein the vent passage extends to a highest surface of the mold cavity.
 5. The system of claim 1, wherein the vented riser sleeve comprises a plurality of vent passages.
 6. The system of claim 1, wherein the mold cavity defines, at least in part, a perimeter of a railcar wheel.
 7. The system of claim 6, wherein the vented riser sleeve further comprises a lip portion that facilitates casting a tread portion of the railcar wheel.
 8. A metal casting system, comprising: a molding flask comprising: a drag mold portion comprising external and internal drag mold walls; a cope mold portion comprising external and internal cope mold walls, wherein the internal drag mold walls and the internal cope mold walls form at least in part a mold pattern cavity representative of a mold pattern; and a vented riser sleeve comprising: a riser reservoir fluidly connected to the mold pattern cavity and configured to allow molten alloy to flow from the mold cavity to the vented riser sleeve; and a vent passage extending through a length of the vented riser sleeve to allow airflow from the mold cavity through the vent passage.
 9. The system of claim 8, wherein the vent passage is cylindrically shaped.
 10. The system of claim 8, wherein the vent passage is rectangularly shaped.
 11. The system of claim 8, wherein the vent passage extends to a highest surface of the mold cavity.
 12. The system of claim 8, wherein the vented riser sleeve comprises a plurality of vent passages.
 13. The system of claim 8, wherein the mold cavity defines, at least in part, a perimeter of a railcar wheel.
 14. The system of claim 13, wherein the vented riser sleeve further comprises a lip portion that facilitates casting a tread portion of the railcar wheel.
 15. A metal casting method, comprising: positioning a vented riser sleeve system within in a flask comprising a mold cavity, the vented riser sleeve extending at least from the flask to the mold cavity, the vented riser sleeve system comprising: a riser reservoir fluidly connected to the mold pattern cavity and configured to allow molten alloy to flow from the mold cavity to the vented riser sleeve; and a vent passage extending through a length of the vented riser sleeve to allow airflow from the mold cavity through the vent passage; and removing the vented riser sleeve from the casting portion.
 16. The metal casting method of claim 15, wherein the vent passage is cylindrically shaped.
 17. The metal casting method of claim 15, wherein the vent passage extends to a highest surface of the mold cavity.
 18. The metal casting method of claim 15, wherein the vented riser sleeve comprises a plurality of vent passages.
 19. The metal casting method of claim 15, wherein the mold cavity defines, at least in part, a perimeter of a railcar wheel.
 20. The metal casting method of claim 19, wherein the vented riser sleeve further comprises a lip portion that facilitates casting a tread portion of the railcar wheel. 